Soaking liquor for dried hides and the like



Patented May 11, 1926.

DOROTHY JORDAN LLOYD AND ROBERT HOWSON ASSIGNORS TO OURSELVES AND THE BRITISH PICKARD, or LONDON, ENGLAND, LEATHER MANUFACTURERS RE- SEARCH ASSOCIATION, OF LONDON, ENGLAND.

SOAKING LIQUOR FOR DRIED HIDES AND THE LIKE.

No Drawing.

This invention relates to an improved method of treatment for dried hides, kips, skins and the like to soften the said hides or the like and has for one of its objects the provision of means whereby the time of treatment is considerably reduced as compared with that necessary when dried hides, kips, skins and the like are merely soaked in water or known soaking liquors containing accelerators in the form of acids or alkalies or substances behaving analogously to acids or alkalies, a further object being to produce a soaked pelt of better substance than can be obtained when known accelerators are used.

Experiments have shown that certain soluble salts which in dilute solution are capable of dispersing serum albumen which has been coagulated by heat will in such dilute solution soften and loosen dried (or drysalted) hides in approximately one third of the time usually required. It is to be understood that in this specification the use of the term polyvalent is to be held to exclude divalency and the use of the expression dried hides is to include drysalted hides in accordance with the usual practice.

- The invention consists in an improved iethod of treatment for dried hides, kips, skins and the like to soften the said hides or the like and comprises soaking the said hides or the like in a dilute aqueous solution of one or more soluble salts which contain polyvalent radicals and form negative polyvalent ions in such dilute solutions, said soluble salts in the concentration employed, being capable of dispersing serum albumen which has been coagulated by heat, but not capable of tanning the pelt.

In order that the invention may be the better understood we will now proceed to describe examples which will enable the in vention to be put into practical effect but obviously many modifications and variations may be introduced to suit particular requirements Soluble salts suitable for use in preparing a soaking liquor according to this invention include sodium citrate, potassium ferro cyanide, sodium ferrocyanide and sodium pyrophosphate and any of these salts in the proportion of approximately one two hundredth of the weight of the anhydrous n1ole- Application filed May 20, 1924. Serial No. 714,566.

cule expressed in pounds dissolved in one hundred gallons of water may be employed.

Specifically, for dealing with average dried kips and skins of average weight either of the following soaking liquors may be employed viz Sodium citrate, 1.3 lbs; water, 100 gal ions; or potassium ferrocyanide, 1.9 lbs; water, 100 gallons; or sodium ferrocyanide, 1.5 lbs; water, 100 gallons; or sodium pyrophosphate, 1.3 lbs; water, 100 gallons.

hen thick average dried hides or thin average dried skins are to be treated greater or less concentration respectively should be used for example either of the following soaking liquors may be used for treating thick average dried hides, viz

Sodium citrate, 2.0 lbs; water, 100 gallons; or potassium ferrocyanide, 2.8 lbs; Water, 100 gallons; or sodium ferrocyanide, 2.2 lbs; water, 100 gallons; or'sodium pyrophosphate, 2.0 lbs; water, 100 gallons; and either of the following for treating thin average dried (or drysalted) skins, viz

Sodium citrate, 1.0 lb; water, 100 gallons; or potassium ferrocyanide, 1.5 lbs; water, 100 gallons; or sodium ferrocyanide, 1.3 lbs; water, 100 gallons; or sodium pyrophosphate, 1.0 lb; water 100 gallons.

Obviously in dealing with dried (or drysalted) hides, kips, skins, and the like it is impossible to absolutely define the best possible concentration for the solutions owing to-the absence of any standard for comparison of such hides and the like and therefore it may be necessary to vary the concentration when the degree of drying, heat of drying, or exposure to sun or other light rays has produced other than an average dried hide, kip, skin or the like.

In some cases more than one of the soluble salts may be included in the prepared soaking liquor provided that no objectionable chemical interaction or reaction takes place; for example a suitable soaking liquor for treating average dried kips or skins of average weight may include Sodium citrate, 0.6 lbs; potassium ferrocyanide, 1.0 lb; water, 100 gallons, or sodium citrate, 0.4 lbs; sodium pyrophosphate, 0.9 lbs; water, 100 gallons.

\Vhen making up soaking liquors in accordance with this invention the effect of the constituents of the water on the negative polyvalent ion which should be present as a result of the solution of the selected salt or salts in the water, must be considered; for example if a Water containing sodium or other alkali carbonate or bicarbonate is to be used the alkali must first be neutralized by the addition of sulphuric acid for example. Alternatively, the alkali may be neutralized by such an acid as will produce one or more of the soluble salts of the type already defined and in such case allowance must be made in calculating the addition required to produce a soaking liquor.

Having now particularly described and as certained the nature of our said invention and in What manner the same is to be performed, we declare that what we claim is 1. An improved method of treatment for dried hides, kips, skins and the like to soften the said hides, comprising the soaking of the said hides in a dilute solution in water of one or more soluble salts which contain polyvalent radicals and form negative polyvalent ions in such dilute solution said soluble salts in the concentration employed being capable of dispersing serum albumen which has been coagulated by heat but not capable of tanning the pelt.

2. In a soaking liquor as claimed in claim 1 the use of a concentration of approximately one two hundredth of the molecular weight of the anhydrous molecule expressed in pounds dissolved in one hundred gallons ot' water.

In testimony whereof we have signed our names to this specification.

DOROTHY JORDAN LLOYD. ROBERT H. PIOKARD. 

